Induced agglomeration system for use in a system for simulating reentry flow conditions

ABSTRACT

A system for simulating reentry flow conditions having a system for accelerating particle to high velocity in an expanding jet of a low molecular weight gas with the particles then used to transfer their energy and momentum to the wind tunnel working gas after they have been separated from the low molecular weight gas. An agglomeration material is supplied to the gas and particle flow near the end of the energy exchange process to provide the larger particle sizes so as to increase the efficiency of the separation of the particles and gas in the Prandtl-Meyer type expansion.

United States Patent [191 Johnson et al.

[4 1 July 29,1975

[54] INDUCED AGGLOMERATION SYSTEM FOR USE IN A SYSTEM FOR SIMULATING REENTRY FLOW CONDITIONS [76] Inventors: Elmer G. Johnson, 54 N. Grand Ave., Fairborn, Ohio 45324; Kenneth R. Cramer, 5596 Hugh Dr., Dayton, Ohio 45459 [22] Filed: Mar. 25, 1974 [21] Appl. No.: 454,200

Primary Examiner.lames J. Gill Assistant Examiner-Anthony V. Ciarlante [57] ABSTRACT A system for simulating reentry flow conditions having a system for accelerating particle to high velocity in an expanding jet of a low molecular weight gas with the particles then used to transfer their energy and momentum to the wind tunnel working gas after they have been separated from the low molecular weight gas. An agglomeration material is supplied to the gas and particle flow near the end of the energy exchange process to provide the larger particle sizes so as to increase the efficiency of the separation of the particles and gas in the Prandtl-Meyer type expansion.

2 Claims, 2 Drawing Figures PATENTED JUL 2 91975 ZUOOFCZ mOkom Oo OP A ED E PM mm 7 w INDUCED AGGLOMERATION SYSTEM FOR USE IN A SYSTEM FOR SIMULATING REENTRY FLOW CONDITIONS RIGHTS OF THE GOVERNMENT The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.

BACKGROUND OF THE INVENTION In apparatus for simulating reentry flow conditions in wind tunnels, such as described in the US. Pat. No. to Johnson et al., 3,739,634, a two-component flow process is employed to produce gas acceleration without dissociation of the gas molecules. Solid particles are accelerated by the drag forces of very high velocity hydrogen jets having velocities substantially higher than can be produced with air because of the high molecular weight of the air. The momentum and energy of the particle cloud, after separation from the hydrogen, is imparted to the wind tunnel working gas.

The particle cloud must be separated from the working gas prior to its entry into the test section. However, the requirements for efficient acceleration of the working gas, which is closely spaced submicron size particles, are exactly opposed to the requirements of any inertial separation process.

BRIEF SUMMARY OF THE INVENTION According to this invention, an apparatus is provided for aiding in the efficient separation of the particle cloud from the wind tunnel working gas without considerably reducing the gas velocity, temperature or pressure. This is accomplished by introducing seed particles into the working gas flow, after the momentum and energy exchange section, to agglomerate the particles and thus make larger diameter particles, which can then be separated easily by a Prandtl-Meyer expansion due to the much greater inertia of the particles. The particles introduced have special agglomeration properties, such as adhesive forces, or electrostatic charges of opposite sign to that carried by the particle cloud.

IN THE DRAWING FIG. I is a schematic diagram of an induced agglomeration system used with an apparatus for generating ultra high total enthalpy gases.

FIG. 2 is an enlarged schematic diagram of the agglomeration system of the device of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIG. 1 of the drawing which shows an apparatus for generating ultra high total enthalpy gases substantially the same as that shown in FIG. 5, of the patent referenced above, wherein particles, normally ofa size between /2 micron and I microns, are supplied through injection means 11 into the flow of a low molecular weight gas such as hydrogen in the input of nozzle 13. The low molecular weight gas, with the particles therein, is accelerated to a high velocity by expanding through the nozzle 13. The particles enter the carrier gas flow of increasingly higher speed and total temperature issuing from nozzles 17, I8 and 19. With the admission of gas on one side of the stream from nozzles 17 and 18 and on the opposite side of the stream from nozzle 19, a focusing effect on the particle stream is produced. The high speed particles enter an air stream issuing from nozzle 20 and the low molecular weight gas passes to a recovery system through channels 22 and 24.

After momentum exchange in region 25, the speed and static temperature of the air is greatly increased. The gas and particles near the end of the momentum exchange region 25 have an agglomeration material from supply 27 added to the stream through line 29, annular feed channel 30 and nozzles 31. In the energy exchange region, the particles are slowing down as they give up their energy to the air. Use is made of this fact near the end of energy exchange region where most of the energy exchange has taken place but where there are still collisions as faster particles come into contact with the slower moving particles ahead of them. An agglomeration material, such as silicon oil, for low static temperature systems, or molten lead, for high static temperature systems, is supplied to the stream near the end of energy exchange region.

In the system shown, a material such as silicone oil in supply 27 is forced through nozzle 31 by means of a gas pressure supplied to piston 32. The agglomeration material used should be a good wetting agent and must not burn at the operating temperature. At operating temperatures below 600F, a material such as Dimethyl siloxane polymer known under the trade name Dow Corning 200 silicone oil in a viscosity range between 500 to 1000 centi-stokes may be used.

For higher operating temperatures, when molten lead is used, a heater, not shown, would be provided to maintain the lead in a molten state. Also, though not shown, a gravity feed system for supplying the agglomeration material may be used for some applications.

In certain applications, the particles may be made of a magnetic material or a material which developes an electrostatic charge during their flow with the air. With such materials, a magnetic field may be provided to increase the collisions between the particles or an electrostatic charge of opposite sign may be provided on the agglomeration material by means of power supply 34 and a collector 36 to aid in the agglomeration process. After agglomeration, the particle sizes will normally be between and 200 microns.

This then provides a more efficient separation of the particle cloud from the high velocity gas flow as the air is expanded in the Prandtl-Meyer type expansion nozzle. The air then passes to the test section through channel 35 and the particles pass to the particle recovery system through channel 37 in the conventional manner.

The operation of the device is substantially the same as the device described in the Johnson et al patent with the addition of the agglomeration of the particles in the region 33.

There is thus provided an induced agglomeration system in an apparatus for generating ultra high total enthalpy gases which provides more efficient separation of the particles and gas in the Prandtl-Meyer type expansion nozzle.

We claim:

1. An induced agglomeration system in combination with an apparatus for generating ultra high total enthalpy gases having a high pressure ratio expansion nozzle; means for supplying a low molecular weight gas to said expansion nozzle to thereby expand the low molecular weight gas to a high speed; means for introducing solid particles of a solid refractory material into the flow of low molecular weight gas whereby the particles are accelerated to the high speeds of the low molecular weight gas; means for separating the low molecular weight gas from the solid particles to thereby provide a separate high energy solid particle stream; means for supplying high temperature air to the solid particle stream; to thereby transfer the energy from the solid particle stream to the air in an energy transfer region and means for separating the solid particles from said air stream; comprising: means for supplying an agglomeration material to the combined solid particle and air eration material is silicone oil.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,896,666

DATED 29 July 1975 lN\/ ENTOR(S) Elmer G. Johnson, Fairborn, and Kenneth R. Cramer,

Ohio

. .Dtaqton It rs certlfle hat error appears m the above-Identified patent and that sard Letters Patent are hereby corrected as shown below:

At page 1, column 1, after Mar. 25, 1974" insert Z75: Assignee: The United States of America as represented by the Secretary of the Air Force, Washington, D.C. At page 1, column 2, after ciarlante insert Attorney, Agent, or Firm Joseph E. Rusz; Richard J. Killoren Signed and Sealed this ninth D ay of December I 975 '[SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Aflesfing ff Commissioner nj'Parenls and Trademarks 

1. An induced agglomeration system in combination with an apparatus for generating ultra high total enthalpy gases having a high pressure ratio expansion nozzle; means for supplying a low molecular weight gas to said expansion nozzle to thereby expand the low molecular weight gas to a high speed; means for introducing solid particles of a solid refractory material into the flow of low molecular weight gas whereby the particles are accelerated to the high speeds of the low molecular weight gas; means for separating the low molecular weight gas from the solid particles to thereby provide a separate high energy solid particle stream; means for supplying high temperature air to the solid particle stream; to thereby transfer the energy from the solid particle stream to the air in an energy transfer region and means for separating the solid particles from saiD air stream; comprising: means for supplying an agglomeration material to the combined solid particle and air stream near the end of the energy transfer region and prior to said separating means; said means, for supplying an agglomeration material to said combined stream, including a plurality of nozzles for directing a flow of agglomeration material into said combined stream and means for supplying the agglomeration material to said nozzles.
 2. The device as recited in claim 1 wherein said solid particles are hafnium oxide particles and said agglomeration material is silicone oil. 